It shouldn’t come as a surprise, but people who regularly monitor their finances end up wealthier than those who don’t. When you were a kid, keeping track of all of your money in a porcelain piggy bank was pretty easy. As we get older, though, our money becomes spread out across things like car payments, mortgages, retirement funds, taxes, and other investments and debts. All of these things make keeping track of our money a lot more complicated.
Refinancing may not be worth it to you, depending on your situation and interest rates, but maybe a reverse mortgage is just what you need. It's typically an option well worth considering for those in or near retirement. A reverse mortgage is essentially a loan, with the amount borrowed not having to be repaid until you die, sell your home, or stop living in it (perhaps because you moved to a nursing home or died). At that time, the home can be sold to cover the debt -- or your heirs can pay it off and keep the home. Reverse-mortgage income is often tax-free, which is another big plus. The amount you get can be delivered in monthly installments, providing very passive and reliable income in retirement.
What happens if you have attrition in your customer base over time. An easy way to extend the model to take this into consideration would be to add a variable to model Attrition Rate as a percentage of the entire installed base at each cycle, and simply subract this from the total population at each cycle. This topic is nicely covered in this blog post by Andrew Chen: Is your website a leaky bucket? 4 scenarios for user retention.
Viral marketing or viral advertising is a business strategy that uses existing social networks to promote a product. Its name refers to how consumers spread information about a product with other people in their social networks, much in the same way that a virus spreads from one person to another. It can be delivered by word of mouth or enhanced by the network effects of the Internet and mobile networks.